Android 4.2.2 allows you to see the battery percentage on the status bar, but if you don’t have android 4.2.2 then follow the below steps to see the battery percentage on your HTC One. HTC One turn off auto correct

For Jelly Bean 4.1.2:
  1. Open “Settings”
  2.  Go to “Power”
  3. There you see the battery percentage

  For Jelly Bean 4.2.2:

  1. Open “Settings”

  2. Go to “Power”

  3.  Mark “Show battery level” to show battery level in status bar